In recent years, materials used for dental restorations have principally comprised methacrylate and acrylate resins referred to herein as “(meth)acrylate resins”. Resinous materials of this type are disclosed, for example, in U.S. Pat. Nos. 3,066,112 to Bowen, 3,194,784 to Bowen, and 3,926,906 to Lee et al. Many of the (meth)acrylate resins used in dental restorations contain units derived from bisphenol A. A common dental resin (meth)acrylate monomer is the condensation product of bisphenol A and glycidyl methacrylate, 2,2′-bis[4-(3-methacryloxy-2-hydroxy propoxy)-phenyl]-propane (BisGMA). Another (meth)acrylate dental resin containing units derived from bisphenol A is ethoxylated bisphenol A dimethacrylate (EBPADMA).
Although present in many common (meth)acrylate resins, Bisphenol A has been linked to a variety of health concerns. It has been found to be present in the urine of 93-95% of adults and children studied. High bisphenol A levels are significantly associated with heart disease, diabetes, and abnormally high levels of certain liver enzymes in humans. It is an endocrine disruptor, and can mimic the body's own hormones, including estrogen, potentially causing adverse health affects.
The bisphenol A containing (meth)acrylate resins are used because of their desired properties including low shrinkage upon curing. Replacement of these resins with other, known (meth)acrylate dental resins, for example 1,6-hexandiol dimethacrylate (HDDMA) and tri(ethylene glycol) dimethacrylate do not adequately provide the desired properties for dental uses as the resulting cured compositions exhibit high shrinkage after polymerization. Therefore, there is a perceived need in the art for a dental resin that is free of units derived from bisphenol A while maintaining good shrinkage resistance, good modulus of rupture, low water absorption, and low water solubility.